1. Field of the Invention
The invention relates generally to a method of manufacturing a capacitor in a semiconductor device. More particularly, the invention relates to a method of manufacturing a capacitor in a semiconductor device, which can obtain a high capacitance and a low leakage current in a capacitor using a Ta2O5 film as a dielectric film, in such a way that a first Ru film used as a lower electrode is deposited by an LPCVD method, a mixture plasma process of Ar and H2 is performed, and then a second Ru film is deposited by an LPCVD method to improve the surface roughness of the Ru film.
2. Description of the Prior Art
As a semiconductor device is highly integrated, in order to secure the capacitance of a capacitor using a Ta2O5 film having a conventional MIS (metal-insulator-silicon) structure as a dielectric film, the thickness of the Ta2O5 film is reduced. This method, however, causes increases in the leakage current. In order to solve this problem, a method in which a metal layer is used as a lower electrode to lower the effective thickness and to secure a capacitance and the characteristic of a leakage current, has been attempted. If a metal layer is used as the lower electrode, the characteristic of a leakage current can be improved due to the thin quality of the lower electrode.
For example, in order to form the Ru film as the lower electrode, an LPCVD method is employed. If the Ru film is formed by an LPCVD method, as the surface roughness is poor, some of the Ru film is deposited as the seed layer by a PVD method, and the Ru film is then deposited by the LPCVD method, thus improving the surface roughness. In this case, however, the process is complicated and the step coverage is adversely affected.
A method of manufacturing a capacitor in a semiconductor device includes the steps of depositing a first Ru film on a semiconductor substrate in which a given structure is formed; processing the first Ru film by exciting a mixture plasma of Ar and H2; depositing a second Ru film on the first Ru film to form a second deposited Ru film, then patterning the second deposited Ru film to form a lower electrode; forming a Ta2O5 film on the entire structure; and forming a TiN film on the entire structure and then patterning the TiN film to form an upper electrode.